After approximately 5 minutes of game play, the demo starts to experience heavy lag. All actions are about 1/3 slower than at start. The lag strikes suddenly and without warning, but the timing in consistent. Re-starting the demo does not always fix the lag, usually a browser restart is required to recover normal play. This is on Macbook Pro OX 10.8.5 16GB RAM, 2.7GHz Intel Core i7

As of Nightly 27a01-2013-09-27 The lag starts almost immediately or at least within the first 15 to 30 seconds of play. When starting in full screen